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SMEX02 Aircraft Polarimetric Scanning Radiometer (PSR) Tb Data

Summary

The Polarimetric Scanning Radiometer (PSR) is an airborne microwave imaging radiometer developed and operated by the National Oceanic and Atmospheric Administration (NOAA) Environmental Technology Laboratory. This data set includes brightness temperature (Tb) and soil moisture data. Measurements were taken 25 June through 12 July 2002 in the regional and Walnut Creek Watershed areas in Iowa, USA during the Soil Moisture Experiment 2002 (SMEX02). The PSR/CX band radiometer is similar to the low-frequency channel of the Advanced Microwave Scanning Radiometers (AMSR) on the NASA Aqua and Japanese ADEOS-II satellites. The radiometer operates at V (vertical) and H (horizontal) polarizations. Data are available from NSIDC via FTP.

These data were collected as part of a validation study for the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E). AMSR-E is a mission instrument launched aboard NASA's Aqua Satellite on 04 May 2002. AMSR-E validation studies linked to SMEX are designed to evaluate the accuracy of AMSR-E soil moisture data. Specific validation objectives include assessing and refining soil moisture algorithm performance; verifying soil moisture estimation accuracy; investigating the effects of vegetation, surface temperature, topography, and soil texture on soil moisture accuracy; and determining the regions that are useful for AMSR-E soil moisture measurements.

Gridded files have names such as "IA629.txt" and "WC629.txt." The two-letter prefix indicates the area (IA=regional, WC=Walnut Creek watershed), followed by the month and day.
Ungridded files use the same convention as above, with the addition of a letter A-D, which designates the number of times (1-4) the flight line was flown that day.

2. Detailed Data Description

Format

Data are provided in ASCII text format.

File and Directory Structure

The main directories are regional and watershed, for the two different regions studied. Subdirectories under each of these are gridded and ungridded. The gridded directory contains brightness temperatures. Within the gridded directory is the sm directory, which contains the estimated soil moisture based on the PSR observations.
The ungridded directory contains the raw brightness temperature observations.

File Naming Convention

Gridded files have names such as "IA629.txt" and "WC629.txt." The two-letter prefix indicates the area (IA=regional, WC=Walnut Creek watershed), followed by the month and day.
Ungridded files use the same convention as above, with the addition of a letter A-D, which designates the number of times (1-4) the flight line was flown that day.

Spatial Coverage

Temporal Coverage

Temporal Resolution

Flights took place on June 25, 27, 29 and July 1, 4, 8, 9, 10, 11, and 12 of 2002. All six flight lines were flown every day.

Parameter or Variable

Parameter Description

The first two columns in the data columns are the UTM (northing and easting) and the next
four columns are the brightness temperatures: C-band (7.32 GHz) (V and H)
and X-Band (10.7 GHz) (V and H) observations, respectively. The files in the sm directory have the UTM location followed by the
estimated soil moisture.

Sample Data Record

The following is a sample from the watershed gridded data table "WC627.txt."

3. Data Access and Tools

Data Access

Volume

Related Data Collections

4. Data Acquisition and Processing

Sensor or Instrument Description

The PSR/CX instrument was integrated onto the NASA WFF P3B aircraft in the aft portion of the bomb bay. The PSR scans at a constant incidence angle of 45°. In SMEX02, PSR was flown over the watershed and regional areas. There were four regional flight lines at an altitude of ~8000 m. Two watershed lines at an altitude of ~1500 m covered the Walnut Creek watershed area. Flights took place on June 25, 27, 29 and July 1, 4, 8, 9, 10, 11, and 12 of 2002. All six flight lines were flown every day.

5. References and Related Publications

Please see the SMEX02 site for more information, and the NSIDC SMEX site to access data.